A bad Malwarebytes updates released the last weekend caused the main process of the security product, mbamservice.exe, to experience high CPU usage on Windows systems, up to the point where computers were nearly impossible to use.

Company officials quickly responded to the complaints posted online, and a fix is already available to address the bug. Users are recommended to install the most recent update and reboot computers – two system restarts might be required, Malwarebytes says, because stabilizing the system doesn’t always take place after the first one.

Fix already available for consumers and endpoints

As far as the cause of the bug is concerned, Malwarebytes says it was all because of a protection update shipped on Saturday morning.

“As a side effect of the web protection blocks, the product also spiked memory usage and possibly caused a crash. We have triaged this issue and pushed a protection update that resolves it,” the company says. “The root cause of the issue was a malformed protection update that the client couldn’t process correctly. We have pushed upwards of 20,000 of these protection updates routinely.”

The company recommends users to update Malwarebytes and to restart computers, but in case this doesn’t address the high CPU usage bug, they should download and run MB-CLEAN. If this second workaround doesn’t make any difference either, getting in touch with the company via its forums is the only option.

The company has also posted guidance for endpoints, and you can check all the steps that IT admins need to follow in order to recover systems in the box after the jump. Malwarebytes, however, notes that these systems were not affected if they weren’t running between Friday and Saturday at 11am Pacific Time.

As a temporary workaround before deploying the latest update, users can also disable Web Protection from Settings > Protection or to attempt to update the application from Safe Mode.

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